Apparatus for thawing materials



May m 1950 J. w. FoRsYTHE ETAL. 2,507,775

APPARATUS FOR THAWING MATERIALS Original Filed Jan. 24, 1945 8 Sheets-Sheet l aAA/ETm May 35, H950 J. w. FoRsYTHE ET AL 2,507,775

APPARATUS FOR THAWING MATERIALS Original File@ Jan, 24,- 1945 8 sheets-sheet 2 May i@ E950 J. w. FoRsYTHl-z ETAL 2,507,775

APPARATUS FOR THAWING MATERIALS Original Filed Janf 24, 1.945

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May E? 1950 J. w. FoRsYTHE ET AL 29507375 APPARATUS FOR THAWING MATERIALS Original Filed `Jam; 124-,v 1945 8 Sheets-Sheet 4 j HCISAC HCI2AC g INVENToRs d fj V EDWARD J. SMOTZER AND Y D BY MARY ALICE FORSYTHE j l (XECUTRIX) May 15 1950 J. w. FORSYTHE x-:T AL 2,507,775

APPARATUS FOR THAWING MATERIALS Original l:Filed Jan. 24, 1945 8 Sheets-Sheet 5 INVENToR. EDWARD .1. sMoTzER AND .JOHN w. FoRsYTHE (oracEAsEb) BY MARY ALICE FoRsvTHE (ExEcu Rlx ATTORNEY May 16 H950 J. w. FoRsYTHE ET AL 2,507,775

APPARATUS RoR THAWING MATERIALS Original Fild Jan. 24,'1945 8 Sheets-Sheet 6 r INVENTOR. U 0 EDWARD J.smo'rzER AND JOHN w. FORSYTHE (DECEASED), BY MARY ALICE FoRsYTHE ATTORNEY May 16, MSU J. w. FoRsYTHE ET A1. 2,507y775 APPARATUS FOR THAWING MATERIALS Original Filed Jar-x. 24, 1945 8 Sheecs--Sheerl '7 lLl f\ @ag n @o Z g y Bo l o 5 0) Ar *V5 f I u) ID gf Q' LLI 1 g I5 [LU] UJG 2 l l LL O z m N a T o y?, @"9 LL- f AAO N Q A o A 2 fg "u INVENTOR.

EDWARD J. sMoTzER AND JOHN w. FDRSYTHE (Dku), f BY MARY ALICE FoRsYTHE (D G7 ATTDRNY May my 1950 J. w. FoRsYTHE ETAL 2,507,775

APPARATUS FOR THAWING MATERIALS 24, 1945 8 Sheelzs--SheetI 8 Original Filed Jan.

(EXEC TRIX) ATTQRN'EY Patented May 16, 195:9-

UNITED STATES P'ENT `OFFICE APPARATUS FOR THAVVING MATERIALS Original application January 24, 1945, Serial No. 574,436. Divided and this application August 8, 1945, Serial No. 609,639

4 Claims.

This invention relates to an apparatus for heating materials; more particularly it relates to an apparatus for thawing materials in lcontainers such as cars and the like.

One of the objects oi the invention is the provision of apparatus for thawing in a rapid economical manner frozen materials in containers to allow their ready discharge therefrom.

This and further objects of the .invention will become apparent as the description proceeds.

Materials such as ore, limestone, coke, andcoal, as well as other similar materials produced or occurring in broken or granular form are transported most economically in open railroad -cars and the like from which they are discharged at the point of use or storage, either 'from bottom openings in the cars or by mea-ns -oi car dum-pers which invert the entire car. Such discharge of materials is rendered diHicult in cold weather by reason of freezing of the materials in the cars in transit or while standing in the yard due to rain, snow, and ice falling on them. rIhe problem of discharge of the cars .is most serious where the material is shipped from lake ports where it is subjected to the damp atmosphere prevailing in such localities.

Various expedients have been tried in the past to thaw and loosen the frozen materials in the cars sufficiently to permit their ready discharge Itherefrom. Such methods Ahave included the building of wood fires under the cars,y the holding of gas jets against the sides of the cars in various places, and the use of steam baths to which parts of the car or the whole car have been subjected. The rst two methods are obf thorough thawing of the material. Furthermore,

because of the moisture contained in the steam, icing of the apparatus at the thawing station, particularly in very cold weather, inevitably results.

By -use of the apparatus of the .present invention, the difficulties above outlined attendant upon the `use .of .prior thawing methods are overcome. Briefly, the invention .provides means for completely enclosing one or more material lcarrying devices, such as railroad cars, vand for subjecting such vcars in the initial 'portion of the heating cycle to a moderately high temperature which may be, for example, on the order of 750 F., following which the yheat is cut back and the car and its contents allowed to'soal: in the latter part of the cycle at 'a lower temperature, which `may be, -or example, on the order of 250 F. vThe method of heating kdisclosed herein is claimed in application YSerial No. 574,436, led January 24, 1945, .now Patent No.. 2,449,932, dated September 21, 1948. This application is a division of said application Serial No. 574,436. Upon completion of the thawing cycle, the container, which may be, .for example, a railroad car, is transferred to the discharge station, which may be a car dumper, whereupon additional cars are charged into the thawing chamber or enclosure and the thawing cycle repeated. In the preferredembodiment of the apparatus described in the following disclosure Yfor purposes of illustration, the operation of the heating means and of various protective devices are made automatically responsive to -the `travel of `the thawing chamber closure means whereby a minimum of manual control -is required of the operator.

The invention will be more fully understood by reference to the accompanying dra-w-ings, in which:

Figure 1 is a side elevation, partially in section,o.i the thawing chamber;

Figure '2 is a View in cross section of the thawing chamber taken lalong the line II-II of Figure l;

Figure 3 'is a View in cross 'section taken along the line III-III of Figure l;

Figure 4 is a schematic plan View of the -a-pparatus including the thawing chamber, tracks leading thereto, safety devices controlling traffic to and from the thawing chamber, and control devices for the chamber; and

Figures 5a, 5b, 5C, 5d and 5e are related schematic Views of the main electrical circuit and the derailer and lig-ht circuits employed in yconnection with the thawing chamber of the illustrated embodiment of the present invention.

The thawing building shown in Figures l, 2, and

3, which may be of brick or other heat-resistant material, is designated generally by the reference character I. Building I consists of a foundation 2, the upper surface of which lies at ground level. The building is provided with ends 3 closing the upper yportions thereof, and with two doors 4 and 5, door 4 to the left of Figure l being sometimes referred to as door #1, and door 5 to the right in Figure 1 being sometimes referred to as door #2. The doors are each provided with a hoisting mechanism, whereby they are lifted sufficiently to allow railroad cars to enter and leave the chamber, the hoisting mechanism for door 4 comprising top sheaves 5 and lower and hoisting drum 8, the corresponding parts of a similar hoisting mechanism for door 5 being designated 'I and 9, respectively. The motor for each door hoist is provided with a traveling nut type limit switch (see Figure 4), that for door 4 (door #1) being designated 95, and that for door 5 (door #2) being designated 95. i

The lower portion of the thawing building is completed by side walls I0 and II and by ceiling I2 which forms a oor for the upper portion of the structure. The upper portion of the structure I, which houses the gas heating and circulating means subsequently to be described, is provided with sides I3 and roof I5, as shown in Figures 1 and 2.

The lower or thawing chamber of the structure is made wide enough, in the particular embodiment shown, to receive a standard railroad car II, on tracks I6, and a narrow gauge electric pusher locomotive I9, on tracks I8, side by side. Locomotive I9 is provided with a retractible side pusher arm (not shown) which may be advanced to engage the rear of the car to be moved. Such design has been found to lend flexibility to the layout, since the narrow gauge locomotive is not impeded in its travel by the railroad cars, but may proceed to pick up as many or as few cars as are desired. In addition, the space above the narrow gauge track is useful as a walkway when the locomotive is removed and the thawing apparatus is not in use. It is to be understood, however, that other means for moving the cars into and through the thawing device may be employed if desired. Locomotive I9, which is of less height than the cars I'I, runs under overhanging portion of the chamber, which forms a portion of the return air flue, which will be subsequently described.

The heating of the air by which thawing of the material is accomplished is performed by two similar heating devices 2l, located on the oor of the upper portion of the structure. The left-hand heating device 2I in Figure 1 will sometimes be referred to as unit No. 1, and the right-hand device will be referred to as unit No. 2. Each such heating device 2I comprises a combustion chamber 22, into which is directed the flame from oil burner 23. Such burner is provided, as shown in Figures 1 and 4, with an oil supply pipe 24, a steam pipe for supplying steam for atomizing the oil, and a combustion air blower 26 driven by motor 26u for delivering air to the burner through delivery pipe 2Gb. The products of combustion travel longitudinally of combustion chamber 22 upwardly through opening 21 in the rear thereof into mixing chamber 28 where they are intimately admixed with recirculated air from the lower thawing chamber of the apparatus. Such recirculated air travels upwardly from the thawing chamber through uptakes or ilues 29 (see Figure 2), laterally into passage 3D, upwardly and then laterally through passages 3| and then upwardly through passages 32, from which it emerges into the mixing chamber.

Circulating air fan 33, driven by motor 34, draws the mixture of recirculated air and products of combustion from mixing chamber 28 into the housing 35 in which the fan is located, and then discharges it under pressure into discharge duct 36. Each ian 33 is provided with a damper 31 in the discharge pipe thereof, whereby, in the event of failure of one heating device 2I or of any of its attendant parts it may be closed off from duct 36 and the entire heating burden borne by the other heating device.

Discharge ducts 36 are connected to ducts 38, which extend longitudinally of the ceiling of the thawing device, as shown in Figures 1, 2, and 3. Vertical discharge pipes 39 and 4U, pipes 39 being on the right-hand side of Figure 2 and pipes 40 being on the left-hand side, are connected to longitudinal ducts 38 at substantially uniform spaced points. The thawing chamber shown is designed to take two standard ninetyton ore cars coupled end to end. It is for this reason that there is a slightly greater space between the adjacent vertical pipes at the longitudinal center of the chamber, that is, the position of the coupling between cars, than between those elsewhere. Pipes 39, which run only to the top of overhang 20, are each provided with an upper nozzle 4I and a lower nozzle 42, discharging the heated air to the contents of the car, and down the side of the car, respectively. Pipes 4U are provided with upper nozzles 43, which discharge the heated air against the other side of the car. Each pipe 49 is also provided with lower nozzles, alternate pipes having lower nozzles 45 which discharge the heated gas horizontally under the car, and the other pipes 4I] having lower nozzles 44 which discharge the gas upwardly at an angle against the side of the car. Each nozzle is provided with its own independent damper 46, of which one is shown in Figure 2 in conjunction with nozzle 43, to control the delivery of gas therefrom, and each nozzle is preferably made of a sh tail shape to provide a heated gas jet having a broad coverage over the surface of the car and its contents.

The thawing chamber shown in Figures 1, 2, and 3, and above described, is shown schematically in Figure 4 in operative relationship to other mechanism with which it may be employed. As shown, it may be positioned to span the broad gauge tracks I6 and the narrow gauge tracks I8 leading to a car dumper, indicated generally at 41. In Figure 4, railroad cars to be thawed enter the chamber' in the direction of the arrow, and after having been suitably heated, leave the chamber and proceed to the car dumper where the material is discharged therefrom. The broad gauge tracks I8 on the entering side of the chamber, that is, on the side of door 4 (door #1) are provided with a derail device 48, which prevents traiic on such tracks from entering the chamber when either door 4 or door 5 is down. There is also provided, on the entering side, a red and amber traffic signal 49 to indicate when the derailer is on the tracks in operative position and when it is off the tracks, respectively. On the exit side of the chamber, that is, just past door 5 (door #2), broad gauge tracks I6 are provided with a similar derailer 52 which operates simultaneously with derailer 48; on such exit side there is also placed a traffic signal 54 similar to asoman signals 48, and acting simultaneously therewith. On the exit` side there is also provided, adjacent the narrow gauge tracks "La trip arm 53 which is automatically positioned,r when; derailers 48 and 52 are4 on tracks I6, to cut the power from pusher locomotive I9 should the locomotive attempttopass such position to enter the thawing chamber. Also positionedv on the exit side of theV chamber within reach of the locomotive operator is a panel board 55. carrying a manually set timing device 56, a sequence start switch 51B, a Sequence stop switch Ell',v emergency lower switch 58, and emergency stop switch 58A. The controls for the derailer. circuit are located in derail panel board 59likewise positioned` on the exit side'. The sequence start and sequence stop switches, as; well as the emergency door and emergency stop switches, are duplicated on: the entering side of the thawing chamber where. the sequence start and stop switch is designated generally as 50 and the emergency lower and stop switch as t. Sequence starting and stopping and emergency lowering and stopping may thus be carried out from either end of the thawing chamber.

rlhe main portion of the controls for the thawing apparatus are contained in control' room Si), shown at the right oi the thawing chamber in Figure 4. Panel 5I` contains controls for the hoisting devices for both doors as well as the furnace temperature control (Micromax) devices. Panels 62 contain the controls for the naine protective device of the heating means Flameotrols). BoXZa is a junction box, whereas box @2b contains the three temperature control relays 3;-CR, 4,-CR and 5-CR, subsequently to be described. Panels 63 contain the starting devices, for the combustion blower fan motors 26e and panels 64 contain the controls for the motors 34 for the circulating fans. Also shown inthe control room is switch 65 for the 23o-volt D. C. circuit supplying power to the various starting and solenoid coils, switch 86 for the llo A. C. signal circuit, and switch El for the B-volt, three phase, 25-cycle A. C. circuit supplying thev power forv the hoist motors, combustion fan motors, and circulating fan motors.

The burners 23 of heating devices 2| are equipped withk pilots burning by-product gas. Such gasv is suppliedthrough pipes 13a to the burners, and. is control-ledV by solenoid-operated gas regulating valve 13?.` Each burner 23 is also equipped with a combination valve, indicated generally at. 68, consisting of a butterfly valve B9 in pipe 26h from the combustion blower to the burner,4 valve 'win steam pipe 2.5,y and valve El in oil supply pipe 24. All three portions of the combination valve are mechanically connected together by a suitable linkage (not shown) to in.- sure the correct relationship between the air steam, and oil supply at all times. Steam4 supply line 25 is also provided with a solenoid-op,- erated valve la for each burner, and oil supply pipe 24 is provided with a solenoid-operated valve 'i2 for each burner, to-enable the supply of steam and fuel oil to each burner to be automatically controlled by the circuit to be described.

Each combustion air blower` 26 is provided with a pressure responsive means 14, located adjacent thereto. inV pipe 2.611, means 'M functioning in a manner subsequently to be described. Each circulating fan 33 is provided, in the housing thereof, with a thermooouple l5 and a suction switch, 16., the therrnocouple functioning with the Micromax control to maintain the heated air deliveredfrom the heating means with which it.. is associated. at7 the correct temperature, and the suction switch operating, tov shut om its respective heating mechanism shouldVv failure occur inthe circulatingfan or its driveL Thethawing chamber is also provided with a gas bleederY valve 'lilA indicated schematically inFigure 4, said valve l1.; having a; regulating damper operated; by. a pressure control regulating mechanism, where-y by valve 'Il functions torelieve excessivepressure in the thawing chamber. A further switch panel 18 arranged interiorly of the upperl portion ofv the structure but outside the thawing. chamber. Such panel carries a manually operatedy switch 'is for turning the oil supply on and oft, aswitch Se, operating they pilot flames for each burner, switches 8l. operating; each of the combustion blower motors 25a, and Switchesz, for operating cachot the recirculating fan motors 3,4.,

The manner in which the previously described controls and; protective devices ior the thawing chamberv andi the associated means for moving cars into and out, ofA such. chamber operate will be more ully comprehended by consideration of the circuit shown in Figures 5e, 5b, 5, 5d and 5e and, by the following description thereof. Figures 5&5", 5, 5d and taken together, thewires! atthe bottom of Figures 5f, 5P and 5c being conf-l nected to the correspondingly designated wires at the top of Figures 51),. s'and 5%, respectively,

and the wires to the left ofigureV 5d being con.- nected to the correspondingly designated wires. at the top oi Figure 5e, constitute a single circuit diagram, as will be seen.

The electrical circuit; connectingv the door hoists,v combustion fans, recirculating air fans,

pilot flame ignition circuit, and the steam,V gas,`

andoilsolenoid, control circuits, as well.V as a pro,- tective control circuit, is shown in thev diagram shown in Figures 5a, 5b, 5C, 5d ande. The parts making up the main elements of each such circuitY are grouped together. The source of power for the hoist and fan motors consist oiY a 230- volt D` C` supply attached to wires ILI and ILZ. Across suQhsuppIy wires ILE and ILE is connected a protective control circuit, which prevents operation of the hoist. motors and blower fans, and which will close all, gas, oil', and steam solenoidoperated vaives under certain conditions.

Such protective control circuit consists of overload relay contacts GLR. (Figure 5C) voltage relay coil VRC, contacts UVI; (Figure 5e), contacts PRI", contacts. OLE and CL4, contacts P'RZ, and contacts CL2. and OLI. Contacts OLR are o-perated by the coil OLRC in the. overload circuit, coil O-LRC opening: contacts OLR4 when too high a. current flows through the coil. Relay contacts.

UVE, which make or break the circuit through wires 8f3.' and 84,. is inthe control circuit for the derailing devices. Upon loss of voltage in the 18.-`

volt derail circuit, due to fuse failme, relay coii UVIC is deenergized', thus breaking the con,-y nection between wires 83` and 84 and opening the circuit to they coil VRC..

Contact PRt operated byl the pressure responsive:` means 14, located in the air duct from the #l blower fan 2li. This device is short-circui'ted by switch $51 mechanically connected to a push button, on switch panel (t3 mecd for starting4 the #l blower fan. While the blower fan in the. #-1 unitA isoperating the contacts PRA will remain. closed. However, if the unit fai-ls for` such reasonv as shaft, breakage or the failure or the fan trede-liver air for any reason, contact PRI open the circuit tov coil: VRR i Contacts OLS and OLII are overload contacts in the motor circuits (shown at the top of Figure d) of the burner blower 28 of unit #l and of the circulating fan 33 of unit #1, respectively, and 'contacts OL2 and OLI are overload contacts in the motor circuits of the burner blower 26 of unit #2 and of the circulating fan 33 of unit #2, respectively. All of these overload contacts are normally closed, but will'open on thermal overload to their associated motor. Contact PR2 is operated by the pressure switch 14 located in the air duct from the #2 blower fan 26, and is short-crcuited by switch B, mechanically connected to a push button on switch panel 63, used for starting the #2 blower fan 26.

With normal starting, all the above contact devices in the protective control circuit are closed when the main power switches are closed except the switches PRI and PR2. These are closed by the manual operation of the starting push buttons on panel 63 with the consequent closing of switches 85 and B, for the starting of the #l and #2 blower fans 25 respectively. Both buttons are pushed together to start both fans at once and to energize coil VRC.

Energization of relay coil VRC closes contacts VRI, shown in the lower part of Figure 5C, in the No. 1 door control circuit, permitting the closing of contactors for the lifting motors for both doors. Opening of contacts VRI, on the other hand, by deenergizing relay coil VRC, stops the operation of both doors. Energization of relay coil VRC also closes contacts VRZ in the combustion air fan control circuit, which when open prevent operation of the burner and blower fans, and closes contacts VR3, which allows openingr of all solenoid-operated gas, oil, and steam valves, said valves being closed upon opening of contacts VR3.

Connected across supply lines ILI and 112 through contacts VR3 is a pilot flame ignition circuit. Such circuit consists of the pilot starting switch 80 connected in series with a circuit consisting of relay coils 3CRC and CRC connected in parallel. When switch 80 is closed, relay coils 3CRC and 4CRC are energized; a contact 3CR operated by relay coil 3CRC opens the circuit to all solenoid operated oil and steam valves 'I2 and 'I3 respectively, thereby insuring that such valves remain shut. Contact 3CR! at the same time closes a circuit to the solenoid-operated gas valves 13b. These valves admit gas to the pilot flame orice. Energization of relay coil 4CRC closes contacts (not shown) in the power supply of an ignition transformer (not shown) thus causing a spark to jump across the gas located in the pilot flame orifice. The pilot llame will ignite, and when the ame is established, power will flow through the flame path to a relay (not shown) which closes the circuit across lines 86 and 8l (Figure 5d) thus energizing and maintaining a circuit to the relay coil 5CRC. Such burner igniting mechanism is part of a standard unit for such purpose, such as the Flame-otrol. Contacts ECR, closed by energization of relay coil SGRC, will close in the circuit to the pilot on light 88; relay coil 5CRC will be energized, and contacts ECR will stay closed as long as the pilot light is on. Upon releasing pilot switch 80, relays 3CRC and ICRC will be deenergized, thus breaking the circuit by opening contacts 3CRI and establishing a circuit by closing contacts 3CR. Contact 5CRI, operated by relay coil 5CRC, will close and maintain power across the solenoidoperated gas valves 13b, and power through con- 8. tacts 3CR, now'closed will open solenoid-operated steam and oil valves 'I3 and I2 respectively. thus causing the atomizing system to be made ready for the admission of oil.

In making the thawing apparatus of the present invention ready for operation, it is necessary to close all main power and control switches, open all manually operated valves, and then start the #l and #2 blower fans by energizing coils 2MC and 5MG and initiate the pilot ilame. Such procedure must be performed each time the plant is made ready for a thawing run. The apparatus is now ready for the normal sequence start and stop operation for the thawing of cars.

When the operator is ready to start a thawing cycle, the sequence switch 51 (Figure 5e) is closed. This switch operates into the derailing circuit, shown in that figure, through wires NWI and RWI and applies the derail to the track rails. The derailing device is a standard Hays deraller, made by the Union Switch and Signal Company, modiiied only by the addition of relays 200, 202, and 294, subsequently to be explained. In Figure 5e, the circuit is shown in that condition wherein the derails are oif the rails. The derailing circuit is supplied with current from an 18-volt D. C. supply connected to lead B18 and CI8.

Closure of switch 5l by depressing the plunger thereof, places power from the 18-volt power supply on the wires NWI and LWI and breaks the circuit to wire RWI. LWI is connected to locking relay coils L, of which two are shown in series (one set of relays L, N, and R being associated with the derailing device on one side of the ore thawing building, and the other set being associated with the derailing device on the other side of the building) to accomplish unlocking of the derailers in their inoperative position. Current in wire NWI energizes relay coils N to open a valve (not shown) in a compressed air line to move the derailing devices and the trip arm for the power supply to locomotive I9 into operative position, that is, onto the rails. After the derails are in place on the rail, the locking relays L are again energized by means of switches 89 and 9U, which are mechanically connected to the respective derailers in such manner that their rotary contactors (not shown) connect contacts Nos. III) and I I2 to contacts I I and I I6, respectively, in switch 89, and connect contacts Nos. IIG and I2U to contacts |22 and |24, respectively, of switch 90 when the derails are in operative position. Thus the derails are now locked in position.

When switches 89 and S0 are thus shifted, they deenergize relay 3WPR by disconnecting it from the 18-volt circuit. Thereupon the contact 9| of relay SWPR becomes operative to energize the coil of relay 29@ with 18-volt current. Closing of relay 294 closes its contacts 92 in the 25o-volt circuit from wires S3 and 94. Power thus ilows to limit switch contacts LS-fl--I and LS-fl-Z (Figure 5d) and thence to the sequence stop switch 51B and to relay coil LRC, thus energizing such coil.

The relay 291i remaining closed, it becomes necessary to release the circuit set up. This is accomplished by the opening of cam-type limit switches LS--t-I and LS-l-Z immediately after the doors start lowering, such lowering being initiated for both doors by the coil of the LR relay, as will subsequently be explained.

In the derail circuit shown in Figure 5e there is also a 11G-volt lighting circuit for the operation of the signal lights marked Y (yellow) and R (red). The wires for such 11G-volt circuit are marked Bil-l and CIID. Wire B||0 leads to al switch operated by relay I-ZHR, the coil of such relay being connected, as shown, to a switch 9| operated by relay 3WPR, which in turn is operated by the switches 89 and 90 which have, as bee fore explained, rotary contactors mechanically connected to the derails. The rotary contactors are so constructed that when the derails are off the rails the coil of relay SWPR is energized, thus closing the switch associated therewith which controls relay |-2I-IR, and thereby energizing such latter relay, and that when the derails are on the. rails relays 3WPR and |-2HR are deenergized. It is therefore. obvious that, when the derails are oi the rails, current will ilow in wires RW and LW, thus lighting the lights Y, and that when thev derails are in place on the rails current will flow in wires RW and NW, thus lighting the lights R.

The two relays marked 200 and 202 are wired into the derail circuit so that when the doors approach the wide open position, and the chamber is thus ready for removal of the thawed cars and/or the introduction of new unthawed cars, the derails are automatically removed from the rails. The circuit to remove the derails in such manner is from wire 96 to limit switches LSI-I and LSI-2 (Figure 5e) through the interlock of the. relay 202 to the coil of relay 200. Breaking of the circuit through these limit switches causes deenergization of the coils of relays 200 and 202, and thus removal of the derails from the tracks.

Returning now to the energization of the relay coil LRC by the pressing of the sequence start switch 51 and the operation of the derails as described to operative position on the rails and their being locked there, the operation of the door closing circuits, and their construction will now bev explained. Since each door circuit is a replica of the other, only the top circuit, for door #1, will be described.

Thereare three contactsl that close when the relay coil LRC is energized. One of these contacts, LR3 (Figure 5b), in series with the contacts II-M3 and 2|M3 in parallel, will connect the coil LRC to wires 94 and 91, thus allowing the operator to let the push button switch 51 spring back to its normally open position. Coil LRC will still remain energizedv through wire IL2, emergency stop switch 58A (middle of Figure 5a), contacts LRS in series with contacts I |M3 and 2'IM3 in parallel, and the sequence stop push button 51A; negative power for the coil LRC being obtained through the contact VRI and the wire 96.

Another contact LRZ, operated by coil LRC, will connect wire 98 to wire 99- (Figure 5a) operating a latch-type relay coil LTRCv (the operation of this. coil will be explained later) and the relay coil IIDBC,. Contact IIDBI, operated by relay IIDBC, will connect wire 99 toI wire |00 (bottom of Figure 5a), thusv energizing, coils HMC and IZDBC, connected in parallel. Coils HMC and IZDBC are connected to line ILI by the closing of the. ||DBI contact, wire |01., closed contact IIFLD, wire 96, and contactVRI. The coil IZCRC is. connected. to line ILI through contact VRI, wire 96, contact IIFLD, and contact I ISDD. Operation of' coil I-ZCRCv closes a contact IZCRI in the circuit to coil MAC. Coil I ICRC is also connected through a contact I ISDU to wire |02..

For the main motor circuit to #l door for lowering, relay contacts IIKO, IIM, MA, |2DB, IlA, IZA, |i3A must close. The main power ow is from IL2 through relay switch IIKS, overload relay IZOLC, contacts IIKO, and resistance armature circuit of the motor.

|R20. Here the power divides and Hows two ways: the rst path is from point IIAI through the armature P to point I |A2 through resistance IRB to contacts |2DB, when closed, to point |50. The second path is from ||A| through the field Q. At point |50 the two circuits combine and the power flow is through the series brake R to wire IIBI.. The current ilows through relay contacts IAA, IBA, I2A, IIA, contact HM, overload relay IIOLC, and relay switch IIKS to ILI, which is the opposite side of the line. Full voltage, somewhat limited by the resistance |R20, is thus placed on the motor armature and the field in parallel. The power owing through these two paths combine, and all power available combine to release the electrically operated brake R. This combination of circuits and resistance allows the door to lower at a safe speed regardless of the overhauling weight of the door.

As the door lowers to within six inches of thev bottom limit of travel, ISDD, which is the slowdown limit switch in the lowering direction, will open', deenergizing coil IZCRC and thus opening 14A contactor and inserting resistor IRI:` in the This will cause the door to slow down. As the door settlesv to the lower' limit of travel, the final limit switch I IFLD will open, deenergizing coils IIDBC, |2DBC' and IIMC. Deenergizing coil IIMC in turn deenergizes coils IIKOC, IIAC, |2AC and I-3AC, thus removing all power from the main motor circuit and releasing the brake. This operation will stopL the door and apply the brake. The brake bands are applied mechanically by means of heavy springs, and will hold the door in any position upon failure or removal of power.

IlFLD is a traveling nut type limit switch geared to the main hoist drive. All other limi-t switches such as HSDD, llSDU, LS3-I, etc., are a part of a 10-point cam type limit switch 95',y indicated in Figure 4, for door #1,. driven by means of a reduction gear coupled directly to the motor shaft. Door #2 is lowered and raised in the same manner, by the same type of' mechanism and at the same time as door No. l, whose operation has been described. The circuit for the #2 door hoist motor is shown in Figure 5b, where P', Q', and R represent the armature, held, and brake for such motor, respectively. The parts of such circuit which correspond with those for the #l door motor are similarly designated except for a change of the i'lrst numeral from 1 to 2.

During the time interval in which the doors are lowering, other devices are started and: entered into operation. Thus energization of relay coil LRC to start the sequence of control for the door lowering will close a contact LR2 in the relay' closing coil LTRC circuit of a latch type relay LTRC. This will close a contact LTRZ con.- necting wire IL2 through the LTR2 contact to: wire |03 which connects to LSE-I and LSB-2'. Asthe door approaches the half-way position, lowering, LSG-I will close to wire` |04', through the test push button S to wire |05 to the coil 4MC operating the across-the-line starter coil for starting the #l recirculating air fan 33. Afterr a iifteen-second time interval and as the door approaches within six inches of the bottom limit of travel, switch LSE-2 will close to wire |06 through the test push button T to wire |01, tothe coil IMC which will operate the across-theline starter for the #2 recirculating air fan. 33. As the door lowers to within two. or threev inches of the bottom, limit switches LS3`t and LSB-2"A (Figure d) will close from wire IL2 to the fan suction switches 'I6 to the manually operated olif-on switch U, the oil valve solenoids 12, and the CRX relay.

The fan suction switches 'I5 are located in the air ducts for the recirculating fans, andreach suction switch will close in turn as the recirculating air fans start. If for any reason, such as breaking of belts to fans or mechanical breaking of shafts, the fans fail, the opening of suction switches 'I6 will release the oil solenoids 'I2 and close the valves, so as to prevent obtaining a combustible mixture in the heating furnaces or in the thawing chamber.

The relay coil CRXC, upon energization, will close a contact (not shown) in a circuit in the temperature controller, actuating a timing circuit `(not shown) for the initial thawing cycle. 'Ihis timing circuit is controlled from the manually preset, electrically operated time clock 5B.

Also, the temperature controller will, at this time, start positioning the three-way mixing valve 68, which has been previously described. This valve admits the proper mixture of air, oil, and steam to the main burner for maintaining the initial thawing cycle.

To sum up the above procedure, the ore thawing chamber is now in full operation, with both burners delivering the high heat cycle of, for example, approximately 750 for any time period desired; for instance, from 5 to 3() minutes, depending upon the cycle for which the time clock is manually preset. After this high temperature heating period is completed, the clock resets the temperature recorder to, for example, a 250 cycle of heating for any period that will not damage the ore cars in the chamber. Opening the doors will, by the mechanism described, stop any heat cycle and all of the equipment necessary to maintain the heat cycle.

After completion of a thaw cycle, the operator will depress the sequence stop push button 58B (Figure 5a). This will energize the relay coil HRC (Figure 5b). The circuit for this relay is from wire IL2 through the stop push buttons 58A and 58B, through contacts I4AI, IIAI, ZIAI, MAI, push button 58C, to the relay coil HRC, to wire 96, through VRI contacts to wire ILI, which is the opposite side of the line. Operation of coil HRC will energize coil LTRC to close contacts LTR! and LTRZ, latching the LTR switch mechanism to the opposite setting. This will immediately deenergize the coils AMC and IMC of the two across-the-line starters operating the recircultaing air fan starters. Both fans will thus cease operating.

Closing of the HR contacts will also energize the coils IIHC, IICRC, IIMC, I 2DBC, I 4AC, IIAC, I2AC, and I3AC. Closing of the coils I IAC, I2AC, and I3AC will be prevented from operating by restraining coils, the function of which will be explained later.

Referring to the main motor circuit for #l door motor, to initiate the hoisting motion relay coils I IHC and IIMC must be energized, contacts I IH and I IM must be closed, contacts I IDB and I2DB must be open, and relay coils IIAC, IZAC, I3AC and MAC ready to operate. The resulting circuit for the initial start will be from line I L2 through IIKS, IZOLC', IIH, IRB, to armature wire IIAI, to the eld Q, to series brake R, to wire I IBI to resistors IR4, IR3, and IRI, to IIM contactor, coil I IOLC, switch HKS', to ILI.

The #l door hoist motor will start to hoist the door slowly.` contactor IIA will close because coil I IAC is energized from line ILI through contacts IIM2 and IlDBB, through relay coils IIAC, I2AC and I3AC in parallel (coils IZAC and I3AC do not close because of armature current circulating through their restraining coils HCIZAC and HCISAC) through contacts I2DB2, IZDBI, IICR, LRI, HRS, MAI, ZIAI, IIAI and MAI and push buttons 58B and 58A to line IL2. Closing of I IA contactor shortcircuits IRI resistor. The motor then speeds up, hoisting the door faster. When the starting current peak for this step on the motor dies down, restraining coil HCIZAC will allow IZA contactor to close, thus short-circuiting resistance IRB'. The motor will speed up further, hoisting the door faster. When this current peak dies down in restraining coil HCISAC, contactor ISA will close, short-circuiting resistance IR4. The deenergization of coil HCISAC will also close contact I3AI to energize relay coil MAC which closes I 4A contactor and short-circuits resistor IRB, thus allowing full voltage across the motor with corresponding full load current, and, as as result, full speed hoisting of the door.

When the door has risen about two or three inches, limit switches LS3-I and LSB-2 will open, removing power from the oil valve operating solenoids 'I2 which will close; the opening of the CRX relay opening in the temperature controller will position the three-way mixing valve, closing the supply of oil and air completely, and closing down the atornizing steam to a. pressure such as 10 p. s. i. Value for purging purposes, such steam pressure being maintained at this value constantly during the time the doors are open. When the door lifts to approximately 36 inches from the end of its travel at the top, the derails will be removed from the rails. This will operate the traic lights to the yellow position, and will admit traflc through the ore thawing chamber. Within 8 inches of the end of travel upward limit switch IISDU (Figure 5a) will open, removing power from the relay coil IICRC. The opening of contact IICR will open contacts I IA, I2A, I3A, and I4A, and the door hoist mechanism will slow down. When the door has reached the top limit of its travel, limit switch I IFLU (Figure 5a) will open, deenergizing coils IIHC, IICRC, IIMC, and I2DBC. Relay I2DBC is a spring closed contactor which is held open electrically and closed mechanically. The deenergizing of coils II HC, II CRC, and II MC will disconnect all power from the motor circuit, and will allow the brake to apply, thus stopping the door and holding it in the wide open position. At such wide open position of the doors, the oil solenoids 12 will be closed, the three-way mixing valve 68 will be closed, the recirculating air fans will be stopped, the derails will be in inoperative position, and the trac lights will be set to allow traine to proceed through the thawing chamber. Thus the apparatus is then in readiness for the placement of one or more loaded cars within it, and for the subsequent initiation of another thawing cycle.

When using the particular apparatus above described, in the thawing of two ninety-ton ore cars at one time, it has been found that, with heating devices 2I with a rated capacity of 10 million B. t. u. per hour each, a ten-minute preliminary heating period at 50G-700 F., followed by a cut-back to soaking at 20D-250 F. for from 5 to 20 minutes is sufficient to thaw most if not all cars encountered during ordinary winter weather, to an extent sufcient to allow their being `emptied in a satisfactory manner by a car dumper which inverts the cars. It is usually necessary to thaw the material to a depth of only about one inch from the car walls and bottom to accomplish the desired freeing of the material from the car. Under exceptionally severe freezing conditions it may be necessary to increase either the length of the preliminary high temperature heating period or the soaking period, or both, and for iight freezing conditions either or both heating periods may be shortened. Within the scope of the method of the present invention there may be employed, therefore, a preliminary heating at from 500 to 750 F. for from to l5 minutes, and a subsequent heating at from 200 to 250 F. for from 5 to 2G minutes.

Use of the device of the present invention has been found to overcome a serious bottleneck in the handling of ore, limestone, and coke in the winter time. lin addition to the speed and certainty with which such materials may now be dumped after the thawing by such device, it has been found that no injury results to the cars by reason of such heating. The metal work, paint, rubber air hoses, and rubber hose gaskets show no deterioration resulting from such treatment, which is in marked contrast to the damage caused by the previous use of wood lires or gas jets in thawing the cars.

Whereas a particular embodiment of the apparatus has been described for purposes of illustration, it is obvious that numerous variations within the teaching of the invention are obvious to one skilled in the art. The scope of the invention is therefore dened by the appended claims. This application is a division of application Serial No. 574,436, filed January 24, 1945.

We claim:

1. Apparatus for preparing for dumping a railroad car having frozen material therein, which road tracks running through the chamber and the openings therein to allow pai-:sage of a car therethrough, derailing devices positioned for operation on the tracks outside each side of the chamber, means for moving a car on said tracks into and out of the chamber, retractable doors for the openings in the chai-berg means For opening and closing the doors means for heating the car in the chamber by subjecting it to air blasts heated to controlled te' and means responsive to the position of at least one door to place the derailing devices on the tracks and to initiate the heating means when the door approaches the closed position and for stopping the operation of the heating means when the door begins to open and for removing the derailing devices from the tracks when the door approaches wide open position.

2. Apparatus for preparing for dumping a railroad car having frozen material therein, which comprises a thawing chamber having an inner space of a size at least sufficient to receive the car, openings in opposite walls of the chamber of sufficient size to allow passage oi the car, railroad tracks running through the chamber and the openings therein to support the car and to allow passage oi the car therethrough, a parallel set of tracks likewise running through the chamber and the openings in the walls thereof, an electric pusher locomotive on the second set of tracks for pushing at least one car into and out of the chamber, derailing devices positioned'for operation on the car supporting tracks outside each side of the chamber, a retractable arm positioned on the entry side of the chamber in operative relation to a power switch on the electric locomotive to trip said switch and cut oil power to the locomotive if the locomotive passes said arm when the latter is in outwardly extended position, retractable doors for the openings in the chamber, means for opening and closing the doors, means for heating the car in the chamber by subjecting it to air blasts heated to controlled temperatures, and means responsive to the position of at least one door to place the derailing devices on the car supporting tracks, to place the trip arm operating the locomotive switch in operative position and to initiate the heating means when the door approaches the closed position, and means for stopping the operation of the heating means when the door begins to open and for removing the derailing devices from the car supporting tracks and placing the trip arm for operating the locomotive switch in inoperative position when the door approaches wide open position.

3. Apparatus for preparing for dumping a container having frozen material therein, which comprises a heating chamber having an inner space of a size at least sufficient to receive the container, said chamber having at least one opening therein allowing passage of the container, a retractable door for said opening, means for opening and closing said door to allow entrance and exit ci the container, means for subjecting the container in the chamber to hot air blasts, said last named means comprising a combustion chamber, a burner directing combustion llames into the combustion chamber, a chamber for mixing the products of combustion and air and having communication with the combustion chamber, a manifold connected to the mixing chamber, means forcing heated air from the mixing chamber into the manifold, a plurality of conduits connected to the manifold, the distant ends of the conduits being spaced at substantially equal distances along one or more of the surfaces of the container, nozzles on the distant ends of the conduits directed toward the container to cover a major portion thereof with the hot air blasts, and return air ducts leading from the inner space of the heating chamber to the mixing chamber.

4l. Apparatus for preparing for dumping a container having frozen material therein, which comprises a heating chamber having an inner space of a size at least suiiicient to receive the container, means for subjecting the container in the chamber to hot air blasts, said last named means comprising a combustion chamber, an oil burner directing a ila-me into the combustion chamber, means conducting the products of combustion into the heating chamber and directing them against the container therein, a motor driven fan for forcing the products of combustion through the last named means, an oil supply pipe for the burner, a pipe supplying combustion air for the burner, a pipe supplying steam under pressure to the burner to atomize the oil, a gas pilot for the burner, solenoid-operated valves in the oil supply pipe, the combustion air pipe, and the steam supply pipe, and a safety circuit connected to the solenoids of the aforementioned valves, said safety circuit comprising means operating said solenoids upon loss of voltage to MARY ALICE FORSYTHE,

Executria: of the Estate of John W. Forsythe,

Deceased.

The following references are of record in the EDWARD J. SMOTZER.

REFERENCES CITED le of this patent:

UNITED STATES PATENTS Number Name Date Buck Jan. 26, 1904 Number 16 Name Date Newhall Sept. 3, 1918 Muehlenbeck May 17, 1927 Maehlei et al Aug. 9, 1927 Maehler et al. Aug. 9, 1927 Buck Feb. 5, 1929 Schramm Feb. 11, 1930 Robertson July 31, 1934 Engels Mar. 8, 1938 Mayer Aug. 15, 1944 Barnett Oct. 2, 1945 Certificate of Correction Patent No. 2,507,775 May 16, 1950 JOHN W. FORSYTHE, DECEASED, ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 5, line 1l, for the reference numeral 57B read 57 line 12, for 57' read 57B and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the oase in the Patent Office.

Signed and sealed this 5th day of September, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

